Abstract: A thin-film color-selective beam splitter and the method of fabricating the same are disclosed. The method includes the steps of: (i) forming a main prism by a pre-selected material, and deciding a first base angle and a second base angle according to the substance and coating characteristics of the pre-selected material; (ii) coating a first multilayer film and a second multilayer film on two slopes of the main prism, in which tilt angles for coating the first multilayer film and the second multilayer film and tilt angles of light entering and emerging the main prism are different, so that spectra of the first multilayer film and the second multilayer film are different, and the first multilayer film can be a red reflective film and the second multilayer film can be a blue reflective film; and (iii) using the pre-selected material to form interface prisms, and adhering the interface prisms to the main prism, so that light can perpendicularly enter and emerge from surfaces of the prism.

Abstract: A telecentric zoom lens is disclosed that comprises, in order from the magnifying side to the reducing side on an optical axis: first, second, third, fourth, and fifth lens groups having a positive, negative, negative, positive, and positive focal length, respectively. An open aperture is axially disposed between the third and fourth lens groups at the magnifying-side focal position of the combined fourth and fifth lens groups. When zooming from the maximum wide-angle state to the maximum telephoto state, the first, fourth, and fifth lens groups are stationary, while the second lens group axially moves linearly toward the reducing side and the third lens group axially moves along a convex path toward the magnifying side.

Abstract: Temperature, pressure and liquid level parameters are sensed by the variable ratio fiber optic coupler sensor wherein the optical coupling ratio varies in accordance with stress applied to the coupler encapsulant resulting from application of the parameter being sensed. Such use of the coupler sensor is particularly advantageous in fuel tanks, which are subject to spark hazard. Vertical arrays of such sensors are utilized to determine levels of liquids in such fuel tanks. Various sensor configurations are disclosed.